Originally Posted by
schley
So diversity is the key and I have 333k in Lifemiles as I purchased some earlier this year when they are 1.3 cpm or thereabouts to complement my 450k UA miles at the moment. Also carry about 750k AA miles, 160k JAL, 80k BA, 45k Emirates, 35k Qatar to help diversify and have go to currency.
Diversity is useful but I'd avoid buying points speculatively just to have them around. Generally speaking you're better off sitting on the cash given the frequency with which the deals happen rather than investing now in something that could change dramatically - nearly always for the worse - without notice. And LM has definitely done that in the past.
ETA: Ditto for sitting on large balances like that. The points aren't going to go up in value; use them.